Typically, the wheel for automobiles or other vehicles is provided as an assembly of a tire and a wheel. The tire and the wheel each have a manufacturing tolerance within which the material, shape or other properties thereof may be subject to variation during a manufacturing process. For this reason, each of the tire and the wheel has a circumferentially uneven weight distribution shown in its static state (hereinafter referred to as “static imbalance”), and a circumferentially uneven weight distribution caused by its rotational motion (hereinafter referred to as “dynamic imbalance”).
Further, the tire is subject to variation in the force applied thereto in the radial directions when the tire is given a turn (hereinafter referred to as “radial force variation”). On the other hand, the wheel is subject to variation in the runout in the radial directions when the wheel is given a turn (hereinafter referred to as “radial runout”).
The static imbalance and other properties as described above may cause vibration or shimmy of a vehicle body and a jerking motion of the steering wheel while the vehicle is running. Therefore, the static imbalance and the dynamic imbalance which each of the tire and the wheel should be corrected. Moreover, the radial force variation of the tire may preferably be cancelled out by the radial runout of the wheel.
As a method for correcting the static imbalance and the dynamic imbalance, a methodology of aligning a light point of the static imbalance, which is the lightest point in circumferential positions of the tire in the static state, and a heavy point of the static imbalance, which is the heaviest point in circumferential positions of the wheel in the static state, with each other is known in the art.
As a method for canceling out the radial force variation of the tire by the radial runout of the wheel, a methodology of aligning a peak position of a primary component of the high-speed radial force variation of the tire, as exhibited when the tire is being turned at high speed, and a bottom position of a primary component of the radial runout of the wheel with each other has been disclosed (see, for example, JP2002-234316 A).
Furthermore, another methodology has been disclosed (see, for example, JP2000-296707 A) in which a phase difference between the radial force variation and the dynamic imbalance of the tire and a phase difference between the radial runout and the dynamic imbalance of the wheel are determined to assemble together the tire and the wheel having the phase differences close to each other.
However, in the tire/wheel assembling methodology of aligning the light point of the static imbalance of the tire and the heavy point of the static imbalance of the wheel with each other, the radial force variation of the tire and the radial runout of the wheel cannot be resolved. Meanwhile, the radial force variation of the tire and the radial runout of the wheel, unlike the case with unevenness of weight distribution, cannot be resolved after the tire and the wheel are assembled together.
In the tire/wheel assembling methodology of aligning the peak position of a primary component of the high-speed radial force variation of the tire and the bottom position of a primary component of the radial runout of the wheel with each other, the static imbalance and the dynamic imbalance cannot be resolved. As a result, an adjustment weight used to correct the unevenness of the weight distribution would be bigger than that used in the methodology of aligning the light point of the static imbalance of the tire and the heavy point of the static imbalance of the wheel with each other to reduce the unevenness of the weight distribution in advance. Such a bigger adjustment weight would impair the appearance, and go counter to the weight reduction, as well as the cost reduction, of the tire/wheel assembly.
In the tire/wheel assembling methodology of determining a phase difference between the radial force variation and the dynamic imbalance of the tire and a phase difference between the radial runout and the dynamic imbalance of the wheel to assemble together the tire and the wheel having the phase differences close to each other, preliminary steps may be required for measuring and determining the dynamic imbalance and other properties of a plurality of tires and wheels. For that reason, a storage facility for temporarily storing the tires and wheels for which measurements have been carried out would be necessitated. Moreover, in this assembling methodology, a conveyance facility for conveying the temporarily stored tires and wheels to an assembling stage would also be necessitated. Further, in this assembling methodology, the assembling process would be more complicate in comparison with the other tire/wheel assembling methodologies in that this methodology involves the following and other steps of: temporarily storing the tire and the wheel, selecting the combination thereof, and conveying them to the assembling stage, which would disadvantageously prolong the operation time.
Under the circumstances, the method which generally prevails comprises assembling a tire and a wheel in such a manner that the radial force variation of the tire is cancelled out by the radial runout of the wheel, and after assembling the tire and the wheel, correcting the static imbalance and the dynamic imbalance which the tire/wheel assembly has by adding an adjustment weight. Accordingly, the disadvantage of a bigger adjustment weight necessitated still remains unattended.
It would be desired to eliminate the disadvantage of such a bigger adjustment weight impairing the appearance of the tire/wheel assembly, and thus to provide an apparatus and method for assembling a tire and a wheel together, in which an adjustment weight can be minimized so as to improve the appearance, using a simple facility and process.